An adjustable wrench includes a frame and a movable jaw. The frame includes a handle, a fixed jaw, a guiding slot, a hole, and a holding portion. The guiding slot is formed between the handle and the fixed jaw. The hole communicates with the guiding slot. An adjusting screw is rotatably engaged in the hole. The movable jaw includes a guiding portion slidably engaged in the guiding slot. A supporting portion and an adjusting portion are formed at the bottom side of the guiding portion. The supporting portion abuts against the holding portion, and the adjusting portion is engaged with the adjusting screw.